…byl to nakonec trochu opruz dohledat správně uživatele, tak dávám do pléna

SELECT i.AccountName, COUNT(*)
	FROM tbl_ChangeSet AS cs
		LEFT JOIN tbl_IdentityMap im ON cs.OwnerId = im.localId
		LEFT JOIN Tfs_Configuration.dbo.tbl_Identity i ON im.masterId = i.Id
	GROUP BY i.AccountName WITH ROLLUP
	ORDER BY COUNT(*) DESC